Standing-balance training is a crucial therapeutic procedure in rehabilitation of neurologically impaired individuals. Modem concepts of neurological rehabilitation favor task-oriented therapy, where one needs to practice balancing in order to re-learn to balance.
Various neuromuscular disorders reduce the ability of an impaired individual to effectively maintain balance while standing. Impaired individuals can be divided into two groups according to their residual balancing abilities. The first group is comprised of subjects with diminished ability (e.g. hemiparesis, paraparesis and tetraparesis), while the second group is characterized by severe impairment (hemiplegia) or complete loss of balancing abilities (paraplegia and tetraplegia).
The goal of neurological rehabilitation for the group of individuals with diminished balancing abilities is to retrain the residual peripheral and central nervous system in order to develop alternative movement strategies needed to co-ordinate motor behavior as efficiently as possible within the constraints posed by the injury. Different methods facilitating the balance re-learning process have been developed. The common techniques include the use of oscillatory platform movements while the impaired individual is standing on the platform, or to provide biofeedback on weight distribution. Both methods aim to improve balancing abilities in impaired individuals. However, these methods should be applied with caution as the subjects are exposed to situations of destabilization. There is an inherent problem of protecting the subject from falling, which must be solved to ensure safety. Unfortunately, safety implementations in turn pose a significant limitation to the outcome of a training process.
Such methods cannot be applied to the group of severely impaired individuals since they are unable to stand without assistance. Consequently, they are often confined to a sitting position, which can result in various medical complications requiring prolonged and expensive professional medical treatment. A common therapy method for the second group is passive standing in rigid standing frames or tilt tables. These therapies are rather static and hence an unattractive activity since they do not require a sufficient degree of cognitive involvement.
A known device, disclosed in Matja{hacek over (c)}ić and Sinkjwr. A Mechanical Apparatus for Arm-Free Therapeutical Paraplegic Standing, Proc. of the International Biomechanics Workshop, April 1999, Enchede, The Nederlands and in Matja{hacek over (c)}ić, Sinkjmr and Johannesen: Unsupported Standing after Spinal Cord Injury, Proc. of the 4th Annual Conference of the International Functional Electrical Stimulation Society, August 1999, Sendai, Japan provides an impaired individual with a fall-safe balancing environment, where the balancing efforts of a standing individual are augmented by stabilising forces acting at the level of the pelvis in the sagittal and frontal planes of motion, assisting the balancing activity of ankle muscles (sagittal plane) and ankle and hip muscles (frontal plane). The biasing means disclosed comprises two hydraulic motors which may be used for actively biasing a user in a given direction or may be used for providing a resilient effect, described as being equivalent to a passive spring effect. However, a system of hydraulic motors is expensive to produce, complex to operate and requires frequent maintenance to function properly. Moreover, such system is rather space consuming and is all in all only suited for experimental purposes in a scientific context and is not suited for use in rehabilitation training in clinics and in particular not suited for use at home of the individuals in need of training.
Another device, more remote from the present invention, is disclosed in Godall et al: Enhancing postural stability in hemiplegic using externally applied forces, Int. Journal of Rehabilitation, 1985 and in Wing, Allison and Jenner. Retraining and retaining balance after stroke, Bailliere's Clinical Neurology, Vol. 2, No. 1, April 1993, in which the individual is supported by a belt at the hip level on which two actuators act in a horizontal plane in perpendicular directions so that the individual may be supported and at the same time purposely be pushed or disturbed for training and evaluation purposes. This device has the same drawbacks as that which is above-discussed and is intended mainly for scientific purposes.